Regarding a technique for ejecting the liquid material in a constant amount, there has hitherto been a problem that, when the ejection is performed for a long time, the liquid material causes a time-dependent change in viscosity thereof and an ejection amount of the liquid material varies.
In view of such a problem, the applicant has proposed an device for ejecting a liquid in a constant amount, wherein an ejection amount is controlled by adjusting an ejection time in an air-type ejection device for applying air under regulated pressure to a liquid material, which is present in a syringe having a nozzle disposed at its fore end, for a desired time (Patent Document 1).
Recently, with further downsizing and higher-density packaging of chips or with more versatility of application work, there have been not only a demand for continuously performing fine application of the liquid material in a very small amount, but also a need for suppressing a variation in the ejection amount of the liquid material to a lower level. Above all, in the underfill step, even finer application of the liquid material in an even smaller amount is required.
In the underfill step, for the purpose of reinforcing connecting portions 103, a resin 104 as the liquid material is filled into a gap between a semiconductor chip 101 and a substrate 102 by utilizing a capillary phenomenon (see FIG. 1). Therefore, if viscosity of the resin material increases with the lapse of time, a problem arises in that an ejection amount of the resin material through a material ejection port decreases and the capillary phenomenon is insufficiently developed, whereby the material is not filled in an appropriate amount into the gap. In some of various resin materials, which cause large changes in viscosity, the ejection amount decreases 10% or more after the lapse of 6 hours, for example.
A method for carrying out correction of the ejection amount in the underfill step is disclosed in, e.g., Japanese Patent Laid-Open Publication No. 2004-344883 (see Patent Document 2). More specifically, Patent Document 2 discloses a method for ejecting a viscous material onto a substrate by using a jet type dispenser, the method including the steps of preparing a total volume of the viscous material to be ejected and a length over which the total volume of the viscous material is to be ejected, operating the dispenser to apply a plurality of viscous material droplets onto a weight scale, generating a feedback signal representing the weight of the plural viscous material droplets which have been applied onto the weight scale, and obtaining a maximum relative speed between the dispenser and the substrate such that the total volume of the viscous material is ejected over the prepared length.
Also, Patent Document 2 discloses a method further including the steps of obtaining respective volumes of a plurality of viscous material droplets, obtaining a total number of droplets required to provide a volume substantially equal to the total volume, obtaining a distance between adjacent droplets, which is required to distribute the viscous material droplets substantially uniform over the prepared length, and obtaining a maximum relative speed between the dispenser and the substrate such that the total number of viscous material droplets are substantially uniformly ejected over the prepared length.
Patent Document 1: Japanese Patent Laid-Open Publication No. Hei 4-200671
Patent Document 2: Japanese Patent Laid-Open Publication No. 2004-344883